I think he was talking about just popping the shifter out and pouring it in the hole. No need to disturb shift forks or transmission cover.
I would suggest that you fill it to 1/2" below the side plug hole. that is the level I fill mine to. The fluid expands as it heats up.
Yes that is what I meant...it would be the only method that would be reasonable, way easier than messing around under the truck. I agree on the 1/2 below the drain plug hole otherwise you may seep gear oil on the clutch when descending steep slopes.
